JPH0212261A - Electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Field of Industrial Application This invention relates to an electrophotographic photoreceptor used in an electrophotographic image forming apparatus, and more particularly to a photoreceptor for a laser printer using a semiconductor laser as a light source (b) ) Prior art In recent years, image forming apparatuses using an electrophotographic method have appeared that use a semiconductor laser as a light source. The longest oscillation wavelength at which stable high output can be obtained in semiconductor lasers currently in practical use is 780 to 830 nm. However, photoconductors used in -i image forming devices and photoconductors that use Ge-free amorphous silicon as a photoconductive layer have a problem of low sensitivity in the long wavelength region; The practical application of photoreceptors using Ge-containing amorphous silicon (hereinafter referred to as a-SiGe), which has high sensitivity as a photoconductive layer, is expected.
-5iGe has: ■ Long lifespan.

■ It is harmless to the human body.

■ High sensitivity to long wavelengths.

There is an advantage. Conventionally, the plasma CVD method, the swab tapping method, etc. have been used to form (laminate) a-3iGe as a photoconductive layer, and the total content of H and halogen in the photoconductive layer formed by such methods H due to gas
or halogen is contained), the limit was 10 to 40 atχ.

(C) Problem to be solved by the invention However, the conventional photoreceptor (with a photoconductive layer made of a-5iGe)
Hereinafter, it will be referred to as an a-5iGe photoreceptor. ) can reduce the optical bandgap and increase the sensitivity in the long wavelength range compared to those that do not contain Ge, but the dark resistivity is small and the charge retention ability is significantly inferior, and the bright conductivity is low. It was not possible to obtain sufficient photosensitivity and was still insufficient for use as a photoreceptor using the Carlson process. This is because the total content of H and halogen in the photoconductive layer was about 10 to 40 atχ.
This is thought to be because the halogen does not bond to the Ge atom, and the dangling bonds of the Ge atom itself increase with the addition of Ge.

In view of the above problems, it is an object of the present invention to provide an electrophotographic photoreceptor in which the electrical characteristics of a photoconductive layer made of a-3iGe are improved.

(Means for Solving Problem d1) The electrophotographic photoreceptor of the present invention comprises a conductive substrate, Si (1
00-X-Y-Z) Gex Hv Xz (atX
) (However, X: halogen.

o<, <100, 0≦Y, Z<100.

40≦, +2≦65).

Further, it is more desirable that the content of Ge to Si in the amorphous photoconductive layer is 5.3 to 150 atχ.

(e) Effect According to experiments conducted by the present inventors, the total content of H and halogen contained in the a-5iGe photoconductive layer is approximately 40 at%.
If it is above, the dark specific resistance becomes 10110 cm or more, and the charge retention rate can be improved. Furthermore, when the total content of H and halogen exceeds approximately 65atχ, the optical bandgap increases, canceling out the optical bandgap reduction effect by Ge addition and reducing the sensitivity in the long wavelength range, making it difficult to use as a photoreceptor for laser semiconductors. It became inadequate.

Furthermore, the amount of Ge added in the a-5iGe photoconductive layer is S
If it was 5.3 at% or less with respect to il, no effect of Ge addition was observed, the optical band gap was high, and the sensitivity in the long wavelength region was poor. Furthermore, the amount of Ge added is 15% relative to the amount of Si.
When it was 0 at% or more, the dark specific resistance became small (and the charge retention rate became poor).

(FIG. 9 is a schematic diagram of an apparatus for depositing an a-5iGe layer using the electron cyclotron resonance method (hereinafter referred to as ECR method). A similar apparatus is also used when depositing an a-Si layer. used.

The device includes a plasma chamber 1 that generates plasma, and a-3+
It has a deposition chamber 2 in which a Ge layer is deposited. The plasma chamber 1 and the deposition chamber 2 communicate with each other through a plasma extraction window, and are evacuated by an oil diffusion pump and an oil rotary pump (not shown).

The plasma chamber l has a cavity resonator configuration, with waveguides 4 to 2
．． A 45Gllz microwave will be introduced. Note that the microwave introduction window 5 is made of a quartz glass plate through which microwaves can pass. 11□ gases are introduced into the plasma chamber 1. A magnetic coil 6.7 is arranged around the plasma chamber 1. The magnetic coil 6 has a plasma generating magnetic field (875G
), and the magnetic coil 7 forms a diverging magnetic field for drawing out the plasma generated in the plasma chamber 1 to the deposition chamber 2.

A drum-shaped conductive substrate 8 made of, for example, Af is mounted in the deposition chamber 2 . The conductive substrate 8 is rotatably supported by a support, so that a 5i is uniformly distributed over the surface.
Ge is deposited. In addition, in the deposition chamber 2, a5iGe
raw material gas is introduced. The raw material gas is a Si compound containing H or a halogen, a Ge compound containing H or a halogen, etc. Specifically, the Si compound is SiH4,5
iz116. SiF4,5iC14,5it (CI,.

5iH2C12 etc., Ge114+Ge as a Ge compound
F4. GeC1, GeF4. Examples include GeCIz. In addition, when forming a photoconductive layer for positive charging, a B compound etc. is introduced as a raw material gas, and when forming a photoconductive layer for negative charging, a P compound etc. is introduced as a raw material gas, and when forming a surface layer. 0114 etc. will be introduced.

With such a configuration, a-SiGe is deposited on the conductive substrate 8.
To form a layer, first a plasma chamber 1. The deposition chamber 2 is evacuated, and 11□ gas is introduced into the plasma chamber 1 and source gas is introduced into the deposition chamber 2. Next, microwaves are introduced into the plasma chamber 1, and the magnetic coil 6.
At step 7, a magnetic field is generated to excite plasma. The plasma-formed H2 and source gas are guided to the conductive substrate 8 by a divergent magnetic field, and a 5iGe is deposited on the conductive substrate 8. Since the conductive substrate 8 is rotated by the support, it is deposited uniformly on the surface of the conductive substrate 8. In addition, by adjusting the position, size, etc. of the plasma drawer window, aSiGe
Improved layer uniformity.

When forming an a-3iGe layer in such an apparatus, the content of H and halogen in the a-3iGe layer can be adjusted by setting the pressure of the source gas. It is a diagram showing the relationship between content and gas pressure, and the raw material gases used and other experimental conditions are as follows.

Microwave output: 2.5kw Raw material gas: 5il14. Ge114 gas flow FJ
: SiH, +GeH4”120 (sccm) Sift
4/ (Sill<10GOII4) =0.88 Gas pressure: 2.5~5. Omtorr substrate heating: A-5iG was formed by changing the gas pressure within the above range without applying Omtorr substrate heating.
The 11 content of the e photoconductive layer is shown in Figure 1, and as can be seen from the figure, if it is less than 3.5 mtorr, 1
] The content is 40 at% or more, and if it exceeds it, it becomes extremely low to 258 tX or less. The dark specific resistance of the a-3iGe layer formed in this way, the semiconductor laser (830
The bright conductivity (ημτ) when the light source is Ωm) is shown in FIGS. 2 and 3, respectively. As can be seen from the figure, by selecting the gas pressure to be approximately 3.5 mtorr or less, that is, by setting the Hfl in the layer to 40a L2 or more, the dark specific resistance becomes 101 Ωcm or more, and the bright conductivity becomes 10
-5iG with a value of -6 or higher and favorable characteristics for the photoconductive layer of an electrophotographic photoreceptor using a semiconductor laser as a light source.
When the H content in the e-layer exceeds approximately 65 atX, the optical band gap increases, canceling out the long wavelength sensitivity characteristic due to the addition of Ge. Therefore, the H content is 40-6
5 at! degree is preferred, most preferably 40-55
It was about atZ.

Next, the ratio of Si to Ge in the a-5iGe layer will be described. H content in the a-3iGe layer is 43 to 48
Gas pressure (approximately 2.5 to 3.5 mt) so that atX
A5iGe layer was formed by regulating the ratio of Si-based source gas and Ge-based source gas, and the relationship between the Si:Gc ratio in the layer and the properties of a5iGe was investigated. . As a result, Ge is approximately 5.3at compared to Si.
% or less, there was hardly any reduction in the optical bandgap due to the addition of Ge, and the sensitivity in the long wavelength region was poor, making it unsatisfactory as a photoconductive layer of a photoreceptor for a semiconductor laser. Furthermore, when the amount of Ge is approximately 150 at% or more relative to Si, the optical band gap decreases, but the dark specific resistance becomes too small and the charge retention ability decreases, making it unsuitable for the photoconductive layer of an electrophotographic photoreceptor. That's what I found out. i.e. a −5i
The amount of Ge in the Ge layer is 5.3 to 150a for 5iil
tχ, preferably 18-82 atχ, most preferably 4
It was 3-67atX.

As described above, a good photoconductive layer can be obtained by using the ECR deposition apparatus and adjusting the gas pressure of the source gas and the source gas ratio. In addition, when forming a-5iG4, the film formation rate is 0.5 μm/min at the gas pressure (2.5 to 3.5 mtorr) at which the a SiG++ layer with good characteristics is formed, and at other gas pressures. It was possible to form a film faster than when the film was formed using the conventional method, and five to six times faster than the conventional method. That is, this embodiment has the advantage that a high-quality photoconductive layer can be formed at a high deposition rate. Also, during film formation (Sillz)
Since there is no formation of polymer particles mainly composed of n, and no film formation defects occur, it is possible to improve the yield of photoreceptors and to create photoreceptors at low cost.

Note that in the above example, H compounds of Si and Ge are used as the raw material gas for the a-3iGe layer, so the a-5
Although we are talking about Hi in the iGe layer, Si, Ge
When using a halogen compound, the total amount of I (halogen) in the a-3iGe layer is 40 to 65 atχ, most preferably 40 to 55 atχ.

Experimental Example> Although a-3iGeJi used as a photoconductive layer has been described above, an actual electrophotographic photoreceptor has an intermediate layer 11. A photoconductive layer 129 and a surface layer 13 are laminated. Middle layer 11. The surface layer 13 of the photoconductive layer 121 is entirely composed of amorphous silicon, and a layer containing Ge, C, etc. is formed by changing the film forming conditions such as the type of source gas and the flow rate. The actual formation of the a-5iGe% photobody will be described below.

Experimental Example: 1 FIG. 5 is a diagram showing conditions for forming a positively charging photoreceptor (p type). The intermediate layer is an a-5i layer doped with a large amount of B,
The photoconductive layer is an a-5iGe layer doped with a small amount of B, and the surface layer is an a-3iC layer.

The H content of the photoconductive layer formed under the conditions shown in the figure was 46 atX, and when the characteristics of the formed photoreceptor were measured, good results were obtained, particularly excellent charging characteristics. Furthermore, when this photoreceptor was used to form an image using a positive charging laser printer, a high quality image could be obtained.

In addition, during film formation, polymer powder mainly composed of (Sill□)n is not generated, so no film formation defects occur, and the film formation speed and raw material gas usage efficiency are 6 to 10 times higher than conventional methods. Experimental Example 2 in which fairly good results were obtained: Under the manufacturing conditions of the a-3iGe photoreceptor shown in Figure 5, an a-3iGei photoreceptor was created by changing only the gas pressure when forming the photoconductive layer. did. In addition, the gas pressure is 2.5.3.0, 3.5.4.0.4.5.5.0
(mtorr), and the charging characteristics of the prepared photoreceptors and the quality of images formed by the photoreceptors are shown in FIG. In addition, of the above gas pressure, a formed
-5iGe photoreceptor's (1) content is 40 to 65 atX at each gas pressure of 2.5.3.0.3.5. As can be seen from the figure, the H content is 40 to 65 at
When the pressure was X (gas pressure of 2, 5, 3, 0, 3, 5), both the charging characteristics and the quality of the formed image were good.

In Experimental Example 1.2, other H compounds or halogen compounds may be used as the raw material gas for Si and Ge (, B
B2H3°BCl3 or the like may be used as a raw material gas for adding. Further, in order to form a positively charging photoreceptor, in addition to B, A1, Ga, In, etc. may be added. Furthermore, in addition to a-5iC, the surface layer has a-5iNSa-S.
A film of iO or the like may be formed.

Experimental Example 3 FIG. 7 is a diagram showing conditions for forming a negatively charged photoreceptor (n type). The intermediate layer is an a-5i layer doped with a large amount of P,
The photoconductive layer is a 5iGe layer doped with a small amount of P;
The surface layer is an a-5iC layer.

The H content of the photoconductive layer formed under the conditions shown in the figure was 46 atX, and the properties of the photoreceptor thus formed were excellent, particularly in charging properties. Furthermore, when an image was formed using a negatively charging laser printer using this photoreceptor, a high quality image could be obtained.

In addition, during film formation, polymer powder mainly composed of (SiHz)n is not generated, so there are no film formation defects, and the film formation speed and raw material gas usage efficiency are better than conventional methods. I was able to do that.

Experimental Example 4 An a-3iGe photoreceptor was produced by changing only the gas pressure when forming the photoconductive layer under the manufacturing conditions of the a5iGe photoreceptor shown in FIG. 7. In addition, the gas pressure is 2.5.2.8.3.3.3.8.4.3.4.8 (
mtorr), and the charging characteristics of the produced photoreceptor and the quality of the image formed by the photoreceptor are classified into eight types.
Shown in the figure. A 5iG formed behind the above gas pressure
eThe H content of the photoreceptor is 40 to 65 atX.
．． 5.2.8.3.3 at each gas pressure, and the a5iGe5 light body formed at these gas pressures has charging characteristics.

The quality of the formed images was also good.

In Experimental Examples 3 and 4, other H compounds or halides may be used as the raw material gas for Si and Ge;
pH, as the raw material gas for adding.

PCh or the like may also be used. In addition, in addition to P, N, Sb, O, etc. may be added to form a positively charging photoreceptor. Furthermore, in addition to a-5iC, the surface layer includes a-5iN,
A film of a-5iO or the like may be formed.

Note that this a-5iGe layer is layered with the photosensitive part of the image sensor and the liquid crystal in addition to the electrophotographic photoreceptor. α
It can also be applied to the photosensitive section of a device that converts optical information from the outside into an electrical signal, such as the photosensitive section of an element. It is also applicable to devices such as solar cells.

(g) Effects of the Invention The electrophotographic photoreceptor of the present invention increases the dark specific resistance and improves the charge retention ability of the photoreceptor by regulating the total amount of H halogen in the photoconductive layer to 40 to 65 atχ. At the same time, it is possible to increase bright conductivity and improve photosensitivity.

In addition, the content of Ge relative to Si is 5.3 to 150 atz
By regulating the wavelength range, it is possible to reduce the optical band gap and improve the sensitivity of long wavelength light corresponding to semiconductor lasers.

As described above, according to the present invention, the characteristics of a photoreceptor can be improved, and the quality of images formed by this photoreceptor can be improved.

[Brief explanation of the drawing]

Figure 1 shows the relationship between the 11-containing stars of the a-5iGe photoconductive layer formed by the ECR method and the source gas pressure during film formation, and Figures 2 and 3 show the relationship between the source gas pressure and the darkness. FIG. 3 is a diagram showing the relationship between specific resistance and bright conductivity. Moreover, FIG. 4 is a diagram showing the structure of the a-3iGe photoreceptor,
FIG. 5 is a diagram showing the formation conditions of an a-5iGe photoconductor for positive charging, and FIG. 6 is a diagram showing the characteristics of the a-5iGe photoconductor formed by changing the raw material gas pressure in FIG. Figure 7 shows the quality of the image formed. Figure 7 is a diagram showing the formation conditions of a negatively charged a-5iGe photoreceptor. Figure 8 shows the quality of the image formed by changing the raw material gas pressure in Figure 7. FIG. 3 is a diagram showing the characteristics of the a-5iGei light body and the quality of the image formed thereby. Furthermore, the ninth
The figure is a schematic diagram of an aSiGe deposition apparatus using the ECR method. - conductive substrate, 1 - intermediate layer, 2 - photoconductive layer, 3 - surface layer. Figure 1

Claims (2)

[Claims] (1) Conductive substrate and Si_(_1_0_0_-_X_-_Y_-_Z_)G
e_XH_YX_Z (at%) (where X: halogen, 0<_X<100, 0≦_Y_, _Z<100, 40≦
_X+_Y≦65) An electrophotographic photoreceptor having an amorphous photoconductive layer. (2) The electrophotographic photoreceptor according to claim 1, wherein the amorphous photoconductive layer has a Ge content relative to Si of 5.3 to 150 at%.